Analyst David Windley said Friday that WellPoint could beat Wall Street's estimates by the largest amount, as the company's 2013 outlook is conservative and analyst estimates for 2014 are low. Windley said Aetna and Health Net are his top picks in the sector, and he also has "Buy" ratings on UnitedHealth and Humana shares.

Health care use has been depressed in recent years because of the weak U.S. economy. More people are skipping or postponing visits to the doctor and medical procedures. That means health insurers continue to collect premium revenue but don't have to spend as much on medical care.

Windley said investors will also be looking at longer-term trends that are beginning to affect the industry. He said private health care exchanges will ultimately be good news for insurers and will result in more competition but greater operating profits, while enrollment in public exchanges created by the Patient Protection and Affordable Care Act will grow slowly. He said enrollment will probably fall short of the Congressional Budget Office's estimate of 7 million members for 2014.